A certain image forming apparatus, such as a copier or an MFP (Multi-Function Peripheral), has a large capacity sheet feeder which can contain a large amount of sheets before printing. As one of such large capacity sheet feeders, there is a tandem large capacity feeder (hereinafter referred to as a tandem LCF).
The tandem LCF has two spaces in which sheet bundles can be horizontally arranged and contained. A sheet bundle stacking tray called a sheet feed tray is provided at a lower part of one of the spaces, and a sheet bundle stacking tray called a conveyance tray is provided at a lower part of the other space. A sheet bundle of, for example, about 1000 or more sheets can be stacked on each of the sheet feed tray and the sheet conveyance tray.
When a sheet is printed, the sheet is sequentially picked up one by one from the upper side of the sheet bundle stacked on the sheet feed tray. The picked up sheet is used for print processing through a conveyance path.
When a sensor detects that all sheets in the sheet bundle on the sheet feed tray are used, the conveyance tray on which a different sheet bundle is stacked is moved to the sheet feed tray side, and the conveyance tray is stopped at a position where the conveyance tray overlaps the sheet feed tray. Thereafter, the conveyance tray returns to the original position while leaving the sheet bundle stacked thereon on the sheet feed tray. As a result, the new sheet bundle is stacked on the sheet feed tray which became empty, and sheet feeding for a next print operation becomes possible.
Although the conveyance tray returned to the original position is empty, the conveyance tray is constructed to be capable of being pulled out to the outside independently of the sheet feed tray. Thus, even when sheets are being fed from the sheet feed conveyance tray.
It is desirable that ends of the sheet bundle stacked on the sheet feed tray are aligned in a longitudinal direction and a lateral direction (that is, alignment is performed in the longitudinal direction and the lateral direction). When printing is started in a state where the alignment is not performed in the longitudinal direction or the lateral direction, each sheet of the sheet bundle is picked up in such a state that the position of the sheet is shifted in the longitudinal direction or the lateral direction (or both directions), and there is a possibility that printing is performed at an unsuitable position.
In the tandem LCF of the related art, alignment in the movement direction of the conveyance tray (hereinafter, the movement direction of the conveyance tray is called a longitudinal direction, and the alignment in the longitudinal direction is called longitudinal alignment) can be relatively easily performed by pressing the sheet bundle to a side wall of the sheet feeder by the driving force of the conveyance tray.
However, alignment in a direction perpendicular to the movement direction of the conveyance tray (hereinafter, the direction perpendicular to the movement direction of the conveyance tray is called a lateral direction, and the alignment in the lateral direction is called lateral alignment) is insufficient.